title: Alanylclavam biosynthetic genes are clustered together with one group of clavulanic acid biosynthetic genes in Streptomyces clavuligerus.
abstract: Streptomyces clavuligerus produces at least five different clavam metabolites, including clavulanic acid and the methionine antimetabolite, alanylclavam. In vitro transposon mutagenesis was used to analyze a 13-kb region upstream of the known paralogue gene cluster. The paralogue cluster includes one group of clavulanic acid biosynthetic genes in S. clavuligerus. Twelve open reading frames (ORFs) were found in this area, and mutants were generated in each using either in vitro transposon or PCR-targeted mutagenesis. Mutants with defects in any of the genes orfA, orfB, orfC, or orfD were unable to produce alanylclavam but could produce all of the other clavams, including clavulanic acid. orfA encodes a predicted hydroxymethyltransferase, orfB encodes a YjgF/YER057c/UK114-family regulatory protein, orfC encodes an aminotransferase, and orfD encodes a dehydratase. All of these types of proteins are normally involved in amino acid metabolism. Mutants in orfC or orfD also accumulated a novel clavam metabolite instead of alanylclavam, and a complemented orfC mutant was able to produce trace amounts of alanylclavam while still producing the novel clavam. Mass spectrometric analyses, together with consideration of the enzymes involved in its production, led to tentative identification of the novel clavam as 8-OH-alanylclavam, an intermediate in the proposed alanylclavam biosynthetic pathway.
authors.affiliation: Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada.
authors.forename: Nathan J
authors.initials: NJ
authors.lastname: Zelyas
authors.forename: Hui
authors.initials: H
authors.lastname: Cai
authors.forename: Thomas
authors.initials: T
authors.lastname: Kwong
authors.forename: Susan E
authors.initials: SE
authors.lastname: Jensen
mesh_terms: D000900:Anti-Bacterial Agents / Q000096:biosynthesis*; D002851:Chromatography, High Pressure Liquid; D019818:Clavulanic Acid / Q000096:biosynthesis*; D002969:Clavulanic Acids / Q000096:biosynthesis; D004269:DNA, Bacterial / Q000235:genetics; D005798:Genes, Bacterial; D005816:Genetic Complementation Test; D008969:Molecular Sequence Data; D005810:Multigene Family; D016296:Mutagenesis; D009154:Mutation; D016366:Open Reading Frames; D010957:Plasmids; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D021241:Spectrometry, Mass, Electrospray Ionization; D013302:Streptomyces / Q000235:genetics* / Q000378:metabolism
chemical_list: D000900:Anti-Bacterial Agents; D002969:Clavulanic Acids; D004269:DNA, Bacterial; C483963:clavam; D019818:Clavulanic Acid